Perforated pipe

Abstract

A perforated pipe and method of making the same for use in wells, screen and the like, the perforations being in the form of sets of oppositely disposed slits in a tubular member defined along a helical path; the preparation being characterized as self-cleaning and resulting from a balanced forming operation to substantially reduce warpage.

I claim: 
     
       1. A screen of the type described comprising sets of slits disposed along a helical path defined on an elongated tube, the slits of each set being parallel to each other and opening in opposite direction into the interior of the tube, said sets being so spaced along said path as to dispose the sets located 360° from each other along said path in alignment longitudinal of said tube and so spaced from the directly adjacent sets along said path as to provide circumferentially spaced longitudinal extending unslitted tube area. 
     
     
       2. A screen as defined in claim 1 wherein the sets of slits disposed in alignment longitudinally of the tube are spaced by arcuate portions of the tube, the concave sides of the arcuate portions facing the longitudinal axis of the tube and the innermost sides of said arcuate portions defining the inner most part of each slit, and portions of said tube defining the circumference thereof defining the outermost part of each slit of each set and disposed in said path. 
     
     
       3. A screen as defined in claim 1 wherein there is a coated reinforcing tube concentric with and located with said first tube in spaced relation.